Ion pumps and passive cotransport systems are present in the membranes of practically all animal cells to maintain cellular ionic composition, to transport electrolytes and fluid across epithelia, and to maintain an osmotic balance and regulate volume of cells. Furthermore, ion pumps in cell membranes of the cornea and lens have a crucial role in maintaining the transparency of these tissues. The anatomical and functional integrity of the endothelium is critical for maintaining the transparency of the cornea. However, medical management of cell loss and physiological function is limited. Thus, research to develop methods to enhance fluid transport is highly relevant. Cataract is a prevalent health problem for which there is no medical treatment. Many mechanisms contribute to the maintenance of lens transparency. It is clear that among many unknown factors, osmotic equilibrium, Na:K ATPase activity and normal GSH levels are necessary to maintain lens transparency. The overall aim of this proposal is to further characterize: mechanisms of ion transport, fluid transport, membrane permeability, metabolic activity and related physiological parameters relevant to the understanding of corneal and lens cell function. To this aim we will use electrophysiological, radiolabelled-tracer and microspectrofluorometric techniques. The latter will exploit recent advances with ion -sensitive intracellular probes to characterize the transport properties of both cultured cells and intact ocular tissue. We expect to provide models of ion and fluid movement across corneal and lens epithelia and the corneal endothelium.